Process of and apparatus for operating cupolas



May 3, 1927.

F. 'K. VIAL. ET AL PROCESS OF AND APPARATUS FOR OBERATING CUPOLAS FiledJan; 19, 1925 Patented May 3, 1927.

4 UNITED STATES PATENT OFFICE.

FREDERICK K. VIAL, OF LA GRANGE, AND GEORGE S. EVANS, 01 OAK PARK,ILLINOIS, ASSIGNORS TO GRIFFIN WHEEL COMPANY, OF CHICAGO, ILLINOIS, ACORPORATION OF MASSACHUSETTS.

PROCESS OF AND APPARATUS FOR OPERATING CI IPOLAS.

Application filed January 19, 1925. Serial No. 3,221.

In the operation of a foundry cupola, it is the usual custom to depositalternate charges of coke and the metal to be melted, burning thelowermost charge otv coke in 5 contact with the metal and through airadmitted to the bottom of the cupola. The ultimate combustion of thecarbon in the cupola must be and always is incomplete. In practice thecarbon finally burns to about m half by weight of carbon dioxid and halfby weight of carbon monoxid. Incomplete ('OH'IlHlHtiOll is desired inorder to maintain a reducing condition to prevent oxidation of the ironand is necessitated by the cupola construction. The incon'ipletelyburned gases pass out at the top of the cupola and are there burned inthe air or permitted to disburse. Because of this final incompletecombustion a loss of heating value of well upwards of 40% results.

lization of a practical and cfiicient process and apparatus readilyconstructed and adapted for commercial use.

The invention contemplates from certain aspects the removal of a part ofthe hot gas mixture resulting from the combustion of the coke-from arelatively low level in the cupola with the result that. first areducing atmosphere is maintained in the upper portion of the cupola andsecond the amount 5 of gas passing up through the subsequent layers ofcoke and coal being reduced, the passage thereof is at a lower rate and1ncreased opportunity: is provided to extractmaximum sensible heat fromthe portion of the gases rising through the cupola.

A further and important object of the invention is the provision of aprocess for operating cupolas wherein substantial economics both in thefuel and power consumption may be attained in the practical andcommercialv operation of foundry cupolas and this withoutcompensatinglosses occasioned through either reduced or inferior output ordeterkiration of the cupola itself through the practice of theinventedprocess.

Another important object of the invention is the attainment of these andother ends without requiring interference with the ordinary practicesemployed in foundries in the introduction of the materials into thecupola and the removal of the metal from it.

Numerous other objects and advantages of the invention will be apparentas it is better understood from the following description, which, takenin connection with the accompanying drawings, discloses a preferredembodimentthereof.

Referring to the drawings. the single figore is a perspective view of anapparatus embodying our present invention, the parts being broken awayand shown in section.

In the melting of cast iron in a cupola, alternate charges of coke andiron are delivered into the cupola and the lowermost charge of coke isburned at a zone of combustion to which air of combustion is introduced.At this zone the coke burns to a large percent of CO and a'relativelysmall percent of CO. In cupola practice prior to the present inventionthe heat of the combustion of the coke renders incandescent subsequentcharges of coke arranged above the lowermost zone and as the gas assesup through this the percentage of G6 has materially'increased until whenit passed out at the top it frequently has been as high as 40 or morepercent of the rising gases. The specific embodiment of our inventionherein to be described contemplates the removal of a substantial part ofthe gases of combustion from not far above the zone of combustion andbefore substantial conversion of CO gas to CO gas has been accomplished.The removed gases are burned to convert the remaining CO gas to CO gasin a recuperator through which passes the air of combustion to edelivered to the combustion zone. This recuperator, in accordance withthe present invention, is so arranged as to extract from the removedgases the heat of combustion possible in converting the CO gas to CO andthe sensible heat contained in these gases as they leave the'cupola.

The portion of the gases of combustion which is not removed passes on upthrough the successive layers and on out at the top of the cupola. Sincethese gases are greatly reduced in volume they have greater time to passthrough successive layers and a larger percentage of sensible heat isextracted from them than was possible when all the gases passed out atthe top of the cupola. \Ve do not want .it understood, however, that wedesire the invention confined from its broad aspect to any of theseparticular arrangements although they are properly made the subjectmatter of particular claims in this application. From a broad aspect anda full survey of the industry it is claimed herein that this inventionis the first to successfully provide for the preheating of the air tothe foundry cupola with attendant economies and in any manner at alladapted for extended commercial use.

The apparatus shown on the drawing comprises a cupola proper, generallydesignated at 1, having the usual charging door 2 and supports Thecharging door is above the bottom 4 of the cupola a distance sutlicientto permit the desired number of alternating charges and coke and iron tobe deposited. Reference character 5 indicates a wind box or encirclingair chamber, which communicates with the interior of the cupola througha circumferentiallydisposed series of tuyeres 6 spaced apart at equalintervals at the lowermost charge of coke which forms the active zone ofcombustion. The gases of the combustion resulting pass up through thesuccessively arranged charges of coke and iron, heating them in theusualmanner.

The cupola is charged with alternate layers of coke and iron. And ourimproved process of cupola operation contemplates the heating of the airblast for the cupola so that the heated air is delivered to thelowermost layer of coke to burn the same and at a temperaturesufiiciently higher than that of the atmosphere to materially increasethe percentage of carbon dioxide gas as the result of the combustion,and correspondingly to reduce the percentage of carbon monoxide gastherein. And this heated air of the blast'burns the lowermost layer ofcoke and all of the hot products of combustion pass upwardly through thehigher layersof coke and iron to preheat them.

In the embodiment disclosed for carrying out our invention we providethe cupola with a bustle pipe 7 disposed about the cuola andcommunicating with its interiory conduits 8, terminating'in tiers. Thisconstruction is preferably arranged a desired distance above the activezone of combustion and below the charging inlet. These tiers or openings9 are arranged so that a considerable portion of the unburned gasesgenerated by the combustion in the cupola -may be isolated, in thepresent case withdrawn from the cupola, and burned whereby to generateheat to be utilized in preheating bustion Lemae the air blast for thecupola. And While various arrangements for heating the air blast arewithin the contemplation of our invention one of our preferred formsconsists of the heating arrangement illustrated in the drawings whereinthe heater comprises a body 11 mounted on firm supporting legs 12 andhaving a combustion chamber l314 at its bottom. chamber is or may be ofany usual or preferred material and in the present instance is providedwith a fire arch 15 through which extend a number of openings 16 topermit the products of combustion to pass upwardly within the preheater.A hot chamber 17, defined by the arch 15 at the bottom, side walls ofthe heater at its side, and a plate 18 at its top, receives the hotgases of combustion. A plurality of pipes 19 extend through oppositeside walls and across said hot chamber and these pipes open freely intoheaders 21 and 22 at opposite ends.

These pipes are designed and arranged to convey, and form preheatingfines for, the air of combustion for the gases in the comchamber. Thisair is received through a conduit 23 under forced draft, if desired, andthence through a pipe or conduit 24 in which is mounted a control valve25, the purpose of which will be presently more fully explained. Theconduit 24 communicates freely with the inside of header 21 and theheader 22 communicates through a passage 26 with the interior of partlet of the combustion chamber. This partis arranged at the side of thebody 11 and is in effect a mixing chamber as well as'a combustionchamber. A conduit 27 communieates with the chamber 14 and with thebustlepipe 7 already described.

The plate 18 is provided with a plurality of openings, in which aresecured a like number of vertical flue pipes 28, which in turn aresecured in a second plate 29 arranged well above the lower plate 18. Thepipes 28 conduct the hot gases of combustion from the hot chamber 17 toa second chamber 31 above the pipes 28 and plate 29. The chamber 31 isdetermined by the plate 29, the side Walls of the preheater and a topplate 32. Above this plate .is a fourth plate 33 and pipes 34 arearranged through the plates 32 and 33 to conduct the products ofcombustion to a head space 35 at the top of the preheater. which headspace communicates with the waste gas outlet-36 which is or may beprovided with an exhaust fan 37.

It is intended that the air of combustion for the cupola be preheated inthis preheater and we have arranged to conduct it about the pipes 28 and34 throughout a circuitous path. The air is "admitted through conduit 23intothe space between the plates 32 and This combustion sociate 33 andabout the pipes 34. A conduit 39 communicates with this space and withthe interior of the heater beneath the plate 29. WVe provide baflles 41,42, 43, etc., beneath .the plate 29 andabove. the plate 18, and

these baflles extend in from opposite directions so that theair mustpass back. and forth across the preheater as it descends in passingabout thepipes 28.

A conduit 44 communicates with the interior of the preheater just aboveplate 18 and with wind box 5 and serves to carrythe heatedair ofcombustion from the preheater to the cupola.

The reheater is preferably intimately as d with the cupola 30 that thetransferred gasesmay be received'at the combustion chamber of the cupolawhile they are still hot and when desired at a temperature above theirflashing point.

It will be noted that the pipes or flues 19 for the air of combustionfor the preheater are arranged in the hot space 17 so that the cold airpasses through the hot-- test zone in the preheater.

Prior to our invention accurate control of the combustion in the cupolahas been impossible for upon altering the blast the re- -sultant changehas been attended by a change in heating rate too disproportionate to bepractical. Our invention )ermits of the accurate control of the comustion and hasthis result as one of its import-ant objects.

The valve 25 controls the amount of air admitted to the combustionchamber of the preheater and through variation of ,this amount of airthe extent of combustion in the preheater is in/ turn controlled.Through the control of this combustion the temperature of the airadmitted to the cupola is subject to accurate adjustment and t iiswithout,

sacrificin the usual ability to control the blast itse f at the cupola.

It willbe manifest that the employment of our invention produces amaterial sav ing in the amount of fuel required to heat the iron to thedesired temperature, and. by the same token our invention permits andaccomplishes a materialsaving in the amount of air necessary totheoperation of the cupola. this last partly because of the reduced fuelemployed and partly also because of the direct transmission of heat forthe melting of the iron b reason of the preheating. of the air itse f.

, Of course, the saving of air is important in the conduction of thepower necessary to the operation ofthe plant. a t

It is thought that theinvention and many of its attendant advantageswill be understood from the foregoing description, and

it w'll be apparent that various changes may be made in the form,construction and arrangement of the parts without departing within thecupola and burning "to preheat the air of combustion supplied to thecupola.

said gases 1 2. The process of operating a' remelting cupola whichcomprises withdrawing gasesof combustion from the cupola and introduc-'ing air to said gases to burn the same and preheating said air and theair of combustion for said cupola by means of the heat generated by theburningof said gases.

3. The process of operating a remelting I cupola which comprises,charging the cupola with alternate layers of coke and iron, deliveringair at a temperature above that of the atmosphere to the lowermost layerof coke to burn the same, and to cause the resulting products ofcombustion to rise through subsequent alternate layers to preheat saidlayers. 1 v

4. The process-of operating a remeltingcupola which comprises burning ina heater unburned gases resulting from combustion within the cupola andutilizing the heat of said burning gases to heat the air of combustionsupplied to the cupola.

5. A process of operating a remelting cupola which comprises burning ina heater the gases from the cupola combustion and air, and directingboth the air of combustion for the cupola and the air of combustion forsaid gases through said heater,

whereby all of said air ot' combustion is preheated. g

6. The process of operating a'remelting cupola which comprises burningin a heater the gases from the cupola combustion and air, and directingboth the air of combustion for the cupola and theair of-combustion forsaid gases through saidheater and controlling the temperature of the airof combustion delivered to the cupola by vary ing the combustion in saidheater.

7. The process of operating aremelting cupola which comprises burningina heater the gases from the cupola combustion and air, and directingboth the air of combustion for the cupola and theair of combustion forsaid gases through said heater, and controlling the temperature of theair of combustion in said heater through varying the air "of combustionto said heater.

8. The rocess of operating a remelting cupola which comprises burning ina heater the gasesfrom the cupola combustion and air and directing boththe air of combustion for the cupola and the air of combustion for saidgases, through the heater, said air of combustion for the burning of theuses assing through the hotter portion ot the water.

9. The process of operating a remelting cupola which comprisesintroducing air into unburned gases resulting trom gombustion "withinthe cupola to burn said gases and preheating the air blast for saidcupola by means of the heat generated by the burning of said gases.

10. The process of operating a reinelting cupola which comprisesintroducing air into gases resulting from combustion within the cupolato burn said gases, preheating the air blast of said cupola by means ofthe heat generated by the burning of said gases and controlling thecombustion-0t said gases to control the temperature of the blast.

it. The process of operating a remelting cupola which comprises chargingthe cupola with alternatelayers of coke and iron and burning the charge,withdrawing products of combustion from the cupola after they havepassed through-a portion of the charge and utilizing the heat derivedfrom said withdrawn gases to preheat the air blast.

12. The process of operating a remelting cupola which comprises chargingthe cupola with alternate charges of coke and iron and burning the same,passing the products of combustion through the charge of ironabove thelowermost charge of coke while maintaiping' a substantial part of thegas of combustion out of contact with superposed layers of coke wherebyto reduce conversion of CO gas to CO gas.

13. The process of operating a remeltin'g "cnpola whichcomprisescharging the cupola withalternate layers of coke and iron,burning the charge, withdrawing a percentage of the gases of combustionabove the active zone of combustion, whereby the remaining gasespasssubstantially slowly through the superposed layers whereby themaximum sensible heat-is extracted therefrom.

M. The process of operating a remelting cupola whichcompriseschargingthe cupola with alternate layers of coke and iron, introducing gaseousmedium .intosaid cupola at one zone, withdrawing gaseous medium from thecupola at a zone between the layers of combustible material andutilizing the latter medium to effect the thermal characteristics of themediumbeing introduced.

-15. The process out operating a remelting cupola which comprisescharging the cupola with alternate layers of coke'and iron, dischargingthe air at a temperature above that of the atmosphere into the lowermostlayer of coketo burn the same and to cause the resulting products ofcombustion to rise through subsequent alternate layers to preheat saidlayers, and controlling the temperature of said air to control thecharacteristics of the melt within the cupola.

heathen 16. A remelting cupola organization comprising a cupola, heatingmeans for the air blast, means for introducing a portion of the productsof combustion of the cupoia into the heating means, means forintroducing air into the heating means to cause combustion of" theproducts of combustion.

17. A remelting cupola organization comprising a cupola, heating meansfor the air blast, means for introducing a portion of the products ofcombustion of the cupola into the heating means, means for introducingair into the heating means to cause combustion of the products ofcombustion, and means for controlling the temperature of combustionwithin the heating means to regulate the temperature of the air blast.

18. lin a remelting cupola organization, the combination of a cupolaadapted to receive alternate charges of coke and iron, heating means"for the air blast, means for divert 'ing, a portion of the unburnedproducts of combustion and for passing them through the heating means toheat the air blast and means for controlling the temperature of the airblast for controlling the characteristics of the melt.

19. in a remelting cupola organization the combination of a cupolaadapted to receive alternate layers of cokeand iron, an air blastadapted to deliver air to the lowermost layer of coke to burn the sameand whereby to cause the resultant products of combustion tolrisethrough the subsequent alternate layers. of coke and iron, means forpreheating the air blast prior to its delivery to the lowermost layer ofcoke and means for regulating the temperature of the air blast forcontrolling the characteristics of the melt. within the cnpola.

QOJA remelting cupola organization, comprising a cupolaand a combustionpreheater associated therewith, means conducting unburned gasesresulting from primary combustion in the cupola to'said combustionpreheater, and means conveying air of combustion from. said preheater tothe zone of primary combustion in said 'cupola.

2].. A remelting cupola organization, comprising, a cupola provided withmeans for conducting away unburned gases of the primary combustion inthe cupola, a preheater having combustion chamber connected to themeans'conducting said gases from the cupola and adapted to burn saidgases in said preheater, tlues arranged through said preheater forconducting the air of combustion tor the cupola to preheat it prior toits admission to the cupola.

22 A remelting cupola organization, comprising, a cupola, a preheaterhaving a coinbustion chamber, means conducting unburned gases from thecupola to said combustion chamber, flues aranged within the preheaterfor the products of combustion from the combustion chamber and for theair of combustion to the cupola, said flues being arranged to cause thecupola air of combustion to be preheated through the combustion of thegases of said 'cupola.'

23. A remelting cupola organization, comprising, a cupola, a preheaterassociated therewith and having a combustion chamber, means fortransferring unburned gases from said cupola to said combustion chamber,flues arranged in said preheater for conducting cupola air of combustionthrough the heater and for conducting air of combustion for thecombustion .in the preheater through a zone heated by. combustion insaid combustion chamber.

24. A remelting cupola organization comprising a cupola, a preheaterhaving a combustion chamber, means for transferring unburned products ofcombustion from said cupola to said combustion chamber said preheaterhaving flues for passing air' to said combustion chamber, and flues forpassing air to the air blast of the cupola. and flues for the productsof combustion of the combustion chamber of the preheater, said fluesbeing constructed and arranged to preheat both the air for the cupolablast and the air for the combustion chamber of the preheater.

25. A remelting cupola organization, comprising, a cupola, a preheaterhaving a coin- -bustion chamber, means for passing unburned gases fromthe cupola to said combustion chamber, said preheater having flues forthe cupola air of combustion, the air of combustion of the combustionchamber of the reheater, and the products of said coinbustion, saidflues being arranged to preheat air of combustion for the 'cupola and ingreater amount the air of combustion for said combustion chamber. I

26.,A remelting cupola organization, com rising, a cu ola, a preheaterhavinga com ustioncham er, means for transferring unburned gases fromsaid cupola to said 7 combustion chamber, said preheater having flues.for conducting air of combustion through the preheater to preheat thesame and deliver it to the cupola, and means controlling the combustionin said combustion chamber. 5

27. A remelting cupola organization, com- I prising, a cupola having azone of combustion at its bottom, a charging door thereabove, means forremoving unburned gases from said cupola intermediate said zone ofcombustion and said charging door, and an apparatus utilizing saidremoved gas to preheat air of combustion delivered to the cuola.-

28. The process of operating a remelting cupola, which comprises,charging the eupola with alternatelayers of coke and iron,

tei'nate layers, and removing a portion of said products of combustionbefore'they pass through all of said subsequent layers.

30. The process of operating a remelting cupola, which comprises,charging the cupola with alternate layers of coke and iron, supplyingpreheated air to thelowermost layer of coke to burn the same, andremoving a part of the product of combustion just above said lowermostlayer of coke and before its contact with-subsequent layers of coke haspermitted reduction of a substantial part of the carbon dioxid gas tocarbon monoxid.

FREDERICK K. VIAL. GEORGE s. EVANS.

